The Neuropathology Core will coordinate post-mortem retrieval of brains from patients studied in the Clinical Core and will dissect and preserve these brains in an anatomically precise manner. This will permit application of multiple immunocytochemical, molecular biological and biochemical procedures to specific brain regions that also have been subjected to semi-quantitative histologic assessment of Alzheimer's disease abnormalities (senile plaques, neurofibrillary tangles, neuronal loss, abnormal neurites) using silver, tinctorial and immunostaining; measurement of senile plaque; differential counts of plaques by type; and biochemical assay of choline acetyltransferase and Alzheimer-related proteins. The results of the neuropathologic and biochemical assessments will be compared with each other and with clinical/neuroimaging assessments in order to assess diagnostic accuracy and identify neuropathologic indices of disease severity and localication that correlate with cognitive defects. These comparisons will test the accuracy of the assessments and provide to collaborating scientists large amounts of well studied brain tissue with a known type and degree of pathology.